Type-C Earphone Pull-Up Circuit for POP Sound Suppression

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Solution Overview

Problem

Electronic devices with USB Type-C interfaces struggle to distinguish between normal and reverse insertion of earphones, leading to POP sounds and functional issues such as impaired audio reception.

Innovation Solution

A pull-up circuit with adjustable resistance values is used to identify earphone insertion type by controlling the access resistance value based on MIC pin voltage, disconnecting the audio path during reverse insertion, and restoring the resistance value post-identification to maintain normal functionality.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If the left and right channels of the earphone are disconnected to eliminate the POP sound, then the POP sound is suppressed, but the electronic device cannot normally recognize normal/reverse insertion of the Type-C plug

Engineering Contradiction:

ImprovePOP soundVSAvoidinsertion type recognition

Core Design Contradiction:

Object-affected harmful factorsVSMeasurement precision

Solution Approach 1:

The patent segments the identification process into two distinct phases: a first identification period with audio path disconnected and pull-up circuit enabled to detect insertion type, and a second identification period with audio path connected and pull-up circuit disabled for normal operation. This temporal segmentation allows the system to achieve both POP sound suppression and accurate insertion recognition without conflict.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent performs preliminary identification of insertion type before connecting the audio path. The controller identifies whether the earphone is normally or reversely inserted during the first identification period when the audio path is disconnected, then uses this information to properly configure the audio path connection in the second period, preventing POP sounds while maintaining recognition accuracy.

Inventive Principle:

Principle #10Preliminary action

2Object-affected harmful factors

If the audio path is disconnected to suppress POP sound, then the harmful sound is eliminated, but the earphone function is affected

Engineering Contradiction:

ImprovePOP soundVSAvoidearphone function

Core Design Contradiction:

Object-affected harmful factorsVSEase of operation

Solution Approach 1:

The patent implements periodic action by alternating between two identification periods: the first period with audio path disconnected for safe insertion detection, and the second period with audio path connected for normal earphone functionality. This periodic switching ensures POP sound suppression during detection while restoring full function during usage.

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The patent makes the audio path connection dynamic rather than static. The controller dynamically switches the audio path between disconnected and connected states based on the identification phase, and dynamically adjusts the pull-up circuit resistance values between first and second resistance values to optimize performance for each phase while maintaining overall system functionality.

Inventive Principle:

Principle #15Dynamics

3Measurement precision

If the pull-up circuit resistance value is increased to reduce MIC pin voltage for reverse insertion detection, then the detection capability is improved, but the original identification logic and button function are affected

Engineering Contradiction:

Improvereverse insertion detectionVSAvoidoriginal function compatibility

Core Design Contradiction:

Measurement precisionVSAdaptability or versatility

Solution Approach 1:

The patent makes the pull-up circuit resistance value dynamic by switching between a first resistance value during the first identification period (when audio path is disconnected) and a second resistance value during the second identification period (when audio path is connected). This dynamic adjustment allows optimized reverse insertion detection during the first period while restoring original functionality during the second period.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent performs preliminary configuration of the pull-up circuit with the first resistance value before insertion detection to ensure accurate reverse insertion identification. After detection is complete, the circuit is restored to its original second resistance value, maintaining compatibility with existing identification logic and button functions.

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS12445774B2Electronic device, pull-up circuit, and method for suppressing pop sound of earphone

Publication Date: 2025.10.14 HONOR DEVICE CO LTD

AI summary

This application relates to the technical field of circuits. An output terminal of the pull-up circuit is configured to be connected to a Type-C plug of the earphone through a MIC pin of the Type-C interface. The controller is configured to control the electronic device to be disconnected from an audio path of the earphone, control an access resistance value of the pull-up circuit to be a first resistance value, and identify normal/reverse insertion of the earphone based on a voltage of the MIC pin of the Type-C interface when the earphone is inserted into the Type-C interface of the electronic device through the Type-C plug. The controller is further configured to control the access resistance value of the pull-up circuit to be a second resistance value after the identification is completed, and the first resistance value is greater than the second resistance value.